Monitor for configuration variable changes#

Each game server build must monitor the server.json file for configuration variable changes. For example, when you allocate a server instance, the IP address, port number, and game mode might contain different values from the previous allocation.

Monitor allocation ID changes#

Each game server instance must detect its allocation ID by monitoring the value of the allocatedID configuration variable in the server.json file. The allocatedID variable value changes each time you allocate or deallocate the server instance. Game server builds also monitor the server.json file to detect its allocation status and its allocation ID.

• When you allocate a server, the value updates to the current allocation ID.
• When you deallocate a server, the value updates to contain an empty string.

Container builds#

If you're using a container build, the server.json file is already mounted into your container. You can find the server.json file location by checking the container's home environment variable.

• For Linux containers, it's in the $HOME environment variable.
• For Windows containers, it's in the $HOMEPATH environment variable.

Best practices#

The recommended way monitor changes to the server.json file depends on the game engine your game is built on.

Unity Engine#

If your game is built using Unity, the recommended way to monitor for configuration variable changes is to use the Game Server SDK.

Unreal Engine#

If your game is built using Unreal Engine, the recommended way to monitor for configuration variable changes is to use the Game Server SDK.

Custom engine#

If you’re using a custom game engine, the recommended way is to use inotify to detect CLOSE_WRITE events. For an example of what a CLOSE_WRITE event looks like, refer to the following inotify log sample.

MODIFY server.json
OPEN server.json
OPEN server.json
CLOSE_NOWRITE,CLOSE server.json
MODIFY server.json
CLOSE_WRITE,CLOSE server.json
OPEN server.json
ACCESS server.json
CLOSE_NOWRITE,CLOSE server.json